Well bore engaging tool



May 13, 1958 lv. EMANul-:L 2,834,579

' WELL BoRE ENGAGING Toor,J

Filed May 21, 195e l /z V 4a 27 `fh @agri/111W@ United States Patent Q WELL Bonn ENoAGnIG 'rootJ Vincent Emanuel, Arcadia, Calif., assignor to Grant Oil Tool Company, Los Angeles, Calif., a corporation of California Application May 21, 1956, Serial No.`586,239

6 Claims. (Ci. 255-73) This invention relates to well tools of a type for engaging and removing material from a well bore wall, and in certain respects is particularly concerned with improved reamer devices.

In well reamers and similar tools, comprising a tool body and a number of cutters or other wall engaging elements carried by the body, it is essential that the wall engaging elements be attached to the body as securely as possible. As will be appreciated, these elements and their mountings are subject to Very great stresses in use and unless securely fastened to the body may break loose and necessitate an expensive and time consuming fishing job. On the other hand though these cutters or other elements should be very securely mounted to the body, they should be mounted in a way permitting their easy removal and replacement.

Improved mounting means for oil well tools such as that described and claimed in U. S. Patent No. 2,695,771 by H. Salvatori et al., issued November 30, 1954, for Tools for Removing Material from Well Bore Walls, assigned to the assignee of the present application ,have achieved excellent results. In some applications, however, in which a wall engaging element is rotatably mounted upon a shaft or pin, and subjected to high loading conditions, mounting means heretofore known to the art have experienced difficulty due to the flexing of the shaft which in turn exerts radially outward forces on the ends of the shaft and upon the bearing mounts for the shaft.

Accordingly, it is an object of the present invention to provide an improved mounting means for oil well tools having a rotatably mounted wall engaging member which eliminates radially outward forces on the mounting means.

It is another object of the present invention to provide an improved mounting arrangement for oil well tools having rotatably mounted wall engaging members which insures retention of the member upon the body when the tool is in use.

It is a further object of the present invention to provide an improved mounting means for such tool elements which facilitates rapid mounting and removal of the elements by means of light fasteners which are not subjected to stresses in use.

The present invention comprises a mounting arrangement for oil well tools in which a wall engaging member is rotatably mounted at a side of the tool body upon a stationary shaft wherein the shaft is non-rotatably mounted in shaft bearing members having bearing recesses into which the ends of the shaft are received and 'il positioned. The radially inward bearing surface of the bearing recesses are substantially equal in radius to the radius of the shaft to allow surface Contact between the shaft and bearings in the radially inward direction. Clearance is provided between the shaft and the bearing v tending rotary reamer cutters ,ing member 18 is slidably engageable with 2,834,579 Patent-ed May 13, 1958 outward movement of the ends of the shaft when the shaft p is flexed. v

The novel features which are believed to be characteristic of the invention, both as to its organization and method of operation, together with further objects and advantages thereof, will be better understood from the following description considered in connection with the accompanying drawing, in which a presently preferred embodiment of the invention is illustrated by way of example. It is to be expressly understood, however, that the drawing is for the purpose of illustration and description only, and is not intended as a definition of the limits of the invention.

Fig. l is aside view of a well reamer embodying the invention;

Fig. 2 is a fragmentary sectional view taken longitudinally through one of the reamer cutters along line 2--2 of Fig. l;

Fig. 3 is an enlarged fragmentary transverse section through the lower cutter mounting member, taken on line 3-3 of Fig. 1;

Fig. 4 is an enlarged fragmentary transverse section through the upper cutter mounting member, taken on line 4 4 of Fig. l;

Fig. 5 is an enlarged fragmentary transverse section similar to Fig. 4` of an alternative embodiment of the present invention.

Referring to Figs. l and 2 the illustrated well teaming tool lll includes a tubular externally cylindrical vertically extending body 11 connectable into a tool string by the usual upper and lower threaded ends l2 and 13. At lo* cations spaced circumferentially about its outer surface, body 11 carries three or more elongated wall engaging members, which in this embodiment, are angularly ex- 14 for engaging and reaming a well bore wall.

Each of the cutters 14 is partially received within an elongated partial cylindrical recess 15 in the body of a diameter only slightly larger than the cutter. At the upper and lower ends of this main cutter receiving recess 15, the body contains a pair of upper and lower reduced dimension auxiliary recesses 16 and 17, within which are received the cutter mounting members. The lower of these auxiliary recesses 17 receives a lower mounting member 18 having a cylindrical upwardly opening bearing recess 19 within which is received and positioned the lower end of a cutter mounting shaft 2l). The mountthe body and retained against displacement radially outwardly of the body by a pair of lateral anges 21 projecting from the member 18 and receivable within undercut grooves 22 in the walls of the auxiliary recess 17 (see Fig. 3). The member 18 is insertable into its illustrated active position within recess 17 by iirst moving the mounting member into the main recess 15 and then sliding the flanges 21 into their respective undercut grooves 22. At its lower end, the mounting member 1S transversely abuts the end wall 23 of the recess 17, and thus abuts the body when in the active position. As shown in Fig. 2, a screw 24 extends through the mounting member 1S and into the body to stabilize the mounting member 18 in its active position. The screw 24 is counterbored or recessed such that the upper surface 25 of the screw head is beneath the radially outer edge of the upwardly opening bearing recess 19, and is preferably at or near the centerline of the shaft bearing recess 19. The bearing recess 19 is extended over part of its cross-sectional area through the mounting member 18 above the upper surface 25 of the screw as described hereinafter.

recess in the radially outward direction to allow free The lower portion 26 of the upper auxiliary recess 16 has a transverse configuration corresponding to that of the lower auxiliary recess 17, as seen in Fig. 4. The side walls of the lower portion 26 of the upper recess have undercut grooves 27 which receive lateral anges 2S on the upper mounting member 3i) for movement toward and away from the main recess 15. The upper portion 31 of the upper auxiliary recess 16 has a width at all points corresponding to the width of the undercut grooves 27 in the lower portion 26 of the auxiliary recess and is substantially equal to, but greater, in length than the length of the upper mounting member 39. Thus, the mounting member 36 may be slid upwardly, into this upper portion 31 of auxiliary recess 16 and then be removed outwardly from the body. A recessed screw 33 retains the upper mounting member 30 in its active position as shown in Fig. 2. The upper mounting member 30 has a cylindrical downwardly opening bearing recess 34 within which the upper end of the cutter mounting shaft 20 is received and positioned.

The cutter mounting shaft 29 is cylindrical throughout the major portion of its length, which is the portion extending through the main recess and upon which the roller cutter 14 bears and rotates. The section 37 of the shaft which is receivable into the downward-ly opening bearing recess 34 of the upper mounting member 39 is non-symmetrical with respect to the bearing recess. in order to provide clearance in the radially outward direction the section 37 of the shaft is reduced in radius or made arcuate with the center of the arc radially inward of the centerline A in Fig. 4. Thus, the diameter of the section 37 along the centerline A is less than the diameter of the bearing recess and a clearance exists between the shaft and the `surface of the bearing recess radially outward of the centerline, or above the centerline A in Fig. 4. The radially inner portion of the section 37 is symmetrical in cross-section and has a radius substantially equal to the radius of the bearing recess 34 to bear against the mounting member with surface contact against the wall of the bearing recess. For example, in the presently preferred embodiment, the section 37 of the shaft which extends into the bearing recess 34 is ground down along the radially outer half of the ysurface above the centerline of the shaft in Fig. 4 approximately 0.015 inch at the maximum point on a shaft having a diameter of 1.25 inches. In addition the reduction in radius is carried slightly below the centerline in Fig. 4 to allow the centerline of the shaft to move radially outward. Thus, a clearance of 0.015 inch is provided for movement of the shaft radially outward within the mounting member. When radially inward force is exerted on the ycutter member, however, the bearing area of the vshaft against the mounting member remains at the maximum. `lf the diameter of the shaft were merely reduced within the mounting member bearing recess 34 to obtain outward clearance, only line 'contact between the shaft and bearing surface would be 1 achieved.

Referring to Fig. 3, the lower section 38 of the shaft 20 which is received within the lower bearing recess 19 is similar in cross-section to the upper section 37 and is formed by reducing the radius along the radially outer portion of the Ishaft ycross-section. inner portion of the shaft is symmetrical and of sufficient length to engage the bearing surface of the lower bearing recess 19.

in order to prevent piay of the shaft within the mounting members 18, 3@ the cylindrical portion 36 of the shaft 2Q is extended slightly beyond the respective edges of the bearing recesses as shown in Fig. 2 to radially position and maintain the s-haft. While insuring proper radial positioning of the shaft the full diameter of the shaft does not extend suiciently into the bearing recesses to interfere with the function of the reduced sections cf the shaft. That is, when a radially inward force is applied to the shaft, the shaft -will flex inward at the center causing the ends to be moved outward,

The radially however, due to the clearance between the shaft and the bearing recess in this direction no outward stress is exerted upon the :mounting members.

To eliminate any possible loss of the fastener 24,! in the hole and to prevent rotation of the shaft 2t) in the presently preferred embodiment the outer section of the shaft 29 is longitudinally extended beyond the lower bearing recess 19 past the outer surface 25 of the fastener 24. The lower bearing recess 19 is formed to accommodate the extension 39 of the shaft. In the embodiment shown, the outer surface of the lower mounting member is removed beyond the bearing area of the member to provide au opening throughout the length of the member radially beyond the surface of the fastener 24. The end of the extension 39 of the shaft then extends through the mounting member 1S and abuts the end wall 23 of the auxiliary recess 17 in the assembled position. Thus, the extension 39 of the shaft covers the recessed fastener and also prevents any rotation of the shaft.

An essentially square locking member 4Z is receivable within the upper portion 31 of the upper auxiliary recess 16 in the body and in the upward retracting .path of the upper mounting member 30 to positively maintain the upper mounting member in its active position. This locking member 42 has a pair of parallel `surfaces at its upper and lower sides extending perpendicularly to the upward path of movement of the upper mounting member, and engaging correspondingly parallel transverse surfaces 43, 44 on the body and mounting member respectively. The width of locking member 42 is substantially equal to the width of the upper portion 31 of the recess 16. The 'locking member is fastened to the tool body by a screw 45, whose head may be protected by reception within a counterbore.

In mounting one of the cutters 14 to the body 11, the

' lower mounting member 13 is inserted in the main rccess 15 and then slid downwardly into the lower auxiliary recess 17, after which the lower mounting member 13 is fastened to the body by the screw 2,4. roller cutter 14 is partially slipped onto the shaft 29 and the upper end 37 of the shaft is placed in the upper bearing recess 34 of the upper mounting member 3?. With the cutter 14 positioned in the main recess 15 the upper mounting member 30 is inserted into the upper portion 31 of the Lipper auxiliary recess lr6 and slid downwardly to its illustrated active position. As the shaft moves downwardly, its lower Iend 38 moves into the bearing recess 19 and the shaft extension 39 continues through the mounting member 18 to abut the end 23 of t-he auxiliary recess 17. Both ends of the shaft are accurately positioned. The screw 33 is aflixed to fasten the upper mounting member 3@ in its active pesition. To positively retain the screw 33 a keeper pin 46 may be inserted through the opening in the mounting member 3i) provided for that purpose. The locking member 42 is then inserted into the upper portion 31 of the recess 16 and attached to the body by the screw 4S. To remove the cutter 14, screws 45 and 33 are removed and the shaft and cutter are slipped out of the body. l

The illustrated mounting arrangement is so designed that the variousv forces exerted against the cutter 14 in operation are all transmitted directly to, and talcen by, the body itself in a manner eliminating any possibility of the failure of the various fasteners 24, 33 and 45, and consequently assuring against the detachment of the cutters from the body by those forces. Movement of the mounting members 13, 30, the shaft 20, or the cutter 14 radially outward from the body is positively prel the locking member 42 to the end wall 43 of the upper auxiliary recess 16. Since the upper and lower `surfaces of the locking member 42 abut the end wall 43 and the upper surface 44 of the mounting member 30 transversely of the upward retl'acting path of the upper mounting member, no appreciable force is exerted against the fastener 45 tending to break the locking member loose from the body. In addition, as radially inward forces on the-cutter 14 cause the shaft 20 to flex, the ends of the shaft within the mounting members are moved outward, however, the clearance provided by the shaft and bearing construction of the present invention allow the ends of the :shaft to move outward without exerting any radially outward force on the mounting members. At the same time maximum bearing area is provided between the shaft and the mounting member during normal operation of the tool.

Referring to Fig. 5, in an alternative embodiment of the present invention the clearance for iiexing of the shaft is obtained by varying the bearing recess 4d from a circular cross-section while maintaining the shaft diameter uniform within the bearing recess. In this alternative embodiment the bearing recesses are formed such that the radially inward half of the recess, that is, the half inward of the centerline of the shaft 2t) in Fig. 2, has a radius substantially equal to the radius of the shaft. The radially outer half of the bearing recess may be of any configuration allowing a clearance, but is most easily formed as a semi-cylinder of increased radius or with the center of the arc oset radially outward.

For continual operation under severe load conditions it is sometimes desirable to orient the bearing recesses at a radial angle to the normal centerline of the shaft to anticipate the position of the shaft during maximum bearing load and thus during maximum iiexure. For example, if the maximum load on the cutter flexes the shaft at an angle of 12 with respect to the normal centerline of the shaft within the bearing recess, the bearing recess is formed as described hereinbefore but inclined at an angle of 12. At maximum iiexure of the shaft, therefore, the total bearing surface of the shaft within the bearing recesses will be in surface bearing contact.

Thus, the mounting means of the present invention for mounting a rotatablek cutter member on an oil well tool facilitates rapid mounting and removal of the elements by means of light fasteners but eliminates any radial stress on the fasteners due to flexure of the shaft. The mounting means further prevents rotation of the shaft and eliminates any wear which would otherwise result from such rotation. Although the present invention has been described in connection with the locking and mounting arrangement disclosed and claimed in U. S. Patent No. 2,695,771, supra, it may be advantageously utilized in other mounting arrangements in which the wall engaging member is rotatably mounted upon a nonrotatable shaft carried radially at a side of an oil tool body.

What is claimed is:

l. A well reamer comprising a reamer body having in its side a main recess and rst and second auxiliary recesses opening into opposite ends of said main recess, a rotatable reamer cutter in said main recess, a shaft mounting said cutter, a mounting member receivable in said flrst auxiliary recess, a sliding connection mounting said first member for sliding movement into said rst auxiliary recess from said main recess and to an active position, said body having a transverse shoulder at an end of said first auxiliary recess facing said main recess and abutting against said first member to take forces exerted thereby, a second mounting member receivable into the second auxiliary recess, a sliding connection cornprising laterally projecting means on said second mounting member and undercut means in the body interfitting with said laterally projecting means to guide the second mounting member for sliding movement in said second auxiliary recess toward and away from the main recess and between an active position retaining the cutter to the body and a retracted position, said second auxiliary recess having a widened portion'at the retracted position of said second member permitting removal of the shaft and cutter when the member is retracted, a rigid locking member attachable to tne body in said widened portion of said second auxiliary recess at a side of the second member away from the main recess and engaging said member to preventits retraction from said active position, said lockingl member having a pair of oppositely facing parallel surfaces extending in planes perpendicular to the path of sliding movement of said second member and abutting against said second member and body re spectively so that forces tending to retract the said second member are transmitted directly therethrough and taken substantially entirely by the body, said parallel faces having portions in alignment in the direction of retraction of said second member, a screw extending through said locking member and connected into said body to removably attach said locking member to said body; said mounting members defining bearing recesses in the side' of said members adjacent said main recess, said shaft extending through said cutter and having end sections receivable into said bearing recesses, said end sections and said bearing recesses being mateable and having surface contact along the arcuate portion of said shaft which is radially inward of a diameter of said bearing recess which diameter is substantially perpendicular to a radius of said body extending through the axial centerline of said recess radially outward, a clearance between the radially outward arcuate portion of said end sections and said bearing recesses which are radially outward of said diameter, and means for preventing the rotation of said shaft.

2. A well reamer comprising a reamer body having in its side a main recess and frst and second auxiliary recesses opening into opposite ends of said main recess, a rotatable reamer cutter in said main recess, a shaft mount* ing said cutter, a mounting member receivable in said first auxiliary recess, a sliding connection mounting said first member for sliding movement into said first auxiliary recess from said main recess and to an active position, said body having a transverse shoulder at an end of said first auxiliary recess facing said main recess and abutting against said first member to take forces exerted thereby, a second mounting member receivable into the second auxiliary recess, a sliding connection comprising laterally projecting means on said second mounting member and undercut means in the body interitting with said laterally projecting means to guide the Vsecond mounting member for sliding movement in said second auxiliary recess toward and away from the main recess and between an active position retaining the cutter to the body and a f retracted position, said second auxiliary recess having a widened portion at the retracted position of said second member permitting removal of the shaft and cutter when the member is retracted, a rigid locking member attachable to the body in said widened portion of said second auxiliary recess at a side of the second member away from the main recess and engaging said member to prevent its retraction from said active position, said locking member having a pair of oppositely facing parallel surfaces extending in planes perpendicular to the path of sliding movement of said second member and abutting against said second member and body respectively so that forces tending to retract the said secondY member are transmitted directly therethrough and taken substantially entirely by the body, said parallel faces having portions in alignment in the direction of retraction of said second member, a screw extending through said locking member and connected into said body to removably attach said locking member to said body; said mounting members defining bearing recesses in the side of said members adjacent said main recess, said shaft extending through said Q cutter and having end sections extending therefrom receivable into said bearing recesses, said bearing recess being a cylindrical recess substantially circular in crosssectional configuration, said end sections of said shaft receivable within said bearing recesses and having a symmetrical cross-sectional configuration at the arcuate portion of said shaft which is radially inward of a diameter of said bearing recess which diameter is substantially perpendicular to a radius of said body extending through the axial centerline of said bearing recess, said symmetrical cross-section having a radius substantiaily equal to the radius of said bearing recess, the arcuate portion of said shaft which is radially outward of said diameter being reduced in radius whereby a clearance between the radially outward portion of said shaft and the surface of said bearing recess is provided, and means for preventing the rotation of said shaft within said bearing recesses.

3. A well reamer comprising a reamer body having in its side a main recess and lirst and second auxiliary recesses opening into opposite ends of said main recess, a rotatable reamer cutter in said main recess, a shaft mounting said cutter, a mounting member receivable in said first auxiliary recess, a sliding connection mounting said first member for sliding movement into said irst auxiliary recess from said main recess and to an active position, said hodyyhaving a transverse shoulder at an end of said lirst auxiliary recess facing said main recess and abutting against said first member to take .forces exerted thereby, a second mounting member receivable into the second auxiliary recess, a sliding: connection comprising laterally projecting means on said second mounting member and undercut means in the body intertting with said laterally projecting means to guide the second mounting member for sliding movement in said second auxiliary recess toward and away from the main recess and between an active position retaining the cutter to the body and a retracted position, said second auxiliary recess having a widened portion at the retracted position of said second member permitting removal of the shaft and cutter when the member is retracted, a rigid locking member attachable to the body in said widened portion of said second auxiliary recess at a side of the second member away from the main recess and engaging said member to prevent its retraction from said active position, said locking member having a pair of oppositely facing parallel surfaces extending in planes perpendicular to the path of sliding movement of said second member and abutting against said second member and body respectively so that forces tending to retract said second member are transmitted directly therethrough and taken substantially entirely by the body, said parallel faces having portions in alignment in the direction of retraction of said second member, a screw extending through said locking member and connected into said body to removably attach said locking member to said ybody; said mounting members defining hearing recesses in the side of said members adjacent said main recess, said shaft extending through said cutter and having end sections extending therefrom receivable into said bearing recesses, said respective end section of said shaft being in surface bearing contact with an arcuate portion of said recess, said bearing surface being equal to less than one-half of the circumference of the cross-section of the bearing recess,

' said bearing surface being radially inward of a diameter of said bearing recess which diameter is substantially perpendicular to a radius of said body extending through the axial centerline of said recess, said lbearing recess and said end section of said shaft thereby defining a substantial clearance between said end section and the wall of said bearing recess at the portion of said recess radially outward of said diameter; means for radially retaining and positioning said shaft; and means `for preventing the rotation of said shafts within said mounting members, whereby said end sections of said shaft may flex radially outward to allow radially inward dexure of said shaft between said members.

4. A well reamer comprising a reamer body having in its side a main recess and first and second auxiliary recesses opening into opposite ends of said main recess, a rotatable reamer cutter in said main recess, a shaft mounting said cutter, a mounting member receivable in said first auxiliary recess, a sliding connection mounting said first member for sliding movement into said first auxiliary recess from said main recess and to an active position, said body having a transverse shoulder at an end of said first auxiliary recess facing said main recess and abutting against said first member to take forces exerted thereby, a second mounting member receivable into the second auxiliary recess, a sliding connection comlaterally projecting means on said mounting member and undercut means in the body interfitting with said laterally projecting means to guide the second mounting member for sliding movement in said second auxiliary recess toward and away from the main recess and between an active position retaining the cutter to the body and a retracted position, first and second screws extending through said first and second mounting members and connected into said body to removably stabilize said mounting members in the active position, said screws being recessed beneath the radially outer face of said mounting members, said second auxiliary recess having a widened portion at the retracted position of said second member permitting removal of the shaft and cutter when the member is retracted, a rigid locking member attachable to the body in said widened portion of said second auxiliary recess at a side of the second member away from the main recess and engaging said member to prevent its retraction from said active position, said locking member having a pair of oppositely facing parallel surfaces extending in planes perpendicular to the path of sliding movement of said second member and abutting against said second member and body respectively so that forces tending to retract said second member are transmitted directly therethrough and taken substantially entirely by the body, said parallel faces having portions in alignment in the direction of retraction of said second member, a third screw extending through said locking member and connected into said body to removably attach said locking member to said body, said mounting members defining bearing recesses in the side of said members adjacent said main recess, said shaft extending through said cutter and having end sections extending therefrom receivable into said bearing recesses, said end sections and said bearing recesses being mateable and having surface contact along the arcuate portion of said shaft which is radially inward of a diameter of said bearing recess which diameter is substantially perpendicular to a radius of said body extending through the axial centerline of said recess, a clearance between the radially outward arcuate portion of said end sections and said bearing recesses, an extension integrally aiixed to the end section of said shaft receivable into said first mounting member, said extension extending from the radially outer portion of said end section through said first mounting member to abut said transverse shoulder of said first auxiliary recess, said extension extending through said first mounting member radially above said rst recessed screw.

5. An oil well tool comprising a body adapted to be lowered into a well, an element rotatably carried at a side of said body and adapted to engage and act upon the well bore wall; attaching means for rotatably mounting said element radially at the side of said body, said attaching means including a shaft, said shaft rotatably mounting said element and extending entirely therethrough, said shaft having first and second end sections extending beyond the ends of said element; first and second mounting members attached to said body to radially mount said shaft, said mounting members each deiining a bearing recess for receiving and positioning said respective end sections of said shaft, said respective end section of said shaft being in surface bearing contact with an arcuate portion of said recess, said bearing surface being equal to less than one-halfof the circumference of the cross-section of the bearing recess, said bearing surface -being radially inward of a `diameter of said bearing recess which diameter is substantially perpendicular to a radius of said body extending through the axial centerline of said recess, said bearing recess and said end section of said shaft thereby defining a substantial clearance between said end section and the wall of said bearing recess at the portion of said recess radially outward of said diameter; means for radially retaining and positioning said shaft; and means for preventing the rotation of said shafts within said mounting members, whereby said end sections of said shaft may flex radially outward to allow radially inward ilexure of said shaft between said members.

6. An oil well tool comprising a body adapted to be lowered into a well, an element rotatably carried at a side of said rbody and adapted to engage and act upon the well bore wall; attaching means for rotatably mounting said element radially at the side of said body, said attaching means including a shaft, said shaft rotatably mounting said element and extending entirely therethrough, said shaft having a first and second end section extending beyond the ends of said element; iirst and second mounting members attached to said body to radially mount said shaft, said mounting members each Vdening a bearing recess for receiving and axially and radially positioning said respective end sections of said shaft, said bearing recess being a cylindrical recess substantially circular in cross-sectional coniiguration, said end sections of said shaft receivable within said bearing recesses and having a syrrnnetrical cross-sectional coniiguration at the arcuate portion of said shaft which is radially inward of a diameter of said bearing recess which diameter is substantially perpendicular to a radius of said body extending through the axial centerline ofv said bearing recess, said symmetrical cross-section having a radius substantially equal to the radius of said bearing recess, the portion of said end section of said shaft which is radially outward of said diameter being reduced in radius whereby a clearance is defined between said end section and the Wall of said bearing recess radially outward of said diameter; and means for preventing the rotation of said shaft within said bearing recesses.

References Cited in the le of this patent UNITED STATES PATENTS 2,100,621 Abegg Nov. 30, 1937 2,134,095 Abegg Oct. 25, 1938 2,695,771 Salvatori et al Nov. 30, 1954 2,698,738 Turner Jan. 4, 1955 

